1. Field of the Invention
The present invention relates to computer systems and more particularly to a computer system having at least two different boot sequences that can be selected by a user depending on how the computer system is powered on.
2. Description of Related Art
Personal computer systems are well known in the art. Personal computer systems have attained widespread use for providing computer power to many segments of today's modern society. Personal computers can typically be defined as a desktop, floor standing, or portable microcomputer that is comprised of a system unit having a single central processing unit (CPU) and associated volatile and non-volatile memory, including random access memory (RAM) and basic input output system read only memory (BIOS ROM), a system monitor, a keyboard, one or more flexible diskette drives, a CD-ROM drive, a fixed disk storage drive (also known as a "hard drive"), a so-called "mouse" pointing device, and an optional printer. One of the distinguishing characteristics of these systems is the use of a motherboard or system planar to electrically connect these components together. Examples of such personal computer systems are IBM's PC 300 series and IBM's Aptiva Series.
One of the first operations to be performed when a computer is turned on is to load initial programs into the main or system memory to provide the basic tools and utilities which define the operations of the computer system. Such initial programs include the BIOS, the operating system and particular applications defined by initialization control information. The initialization control information which causes an initial program load (IPL) includes Power On Self Test (POST) code, IPL control logic (often termed the boot record) and control data. The POST code can be stored in BIOS in a flash memory.
When the computer system is powered on from its power switch, the POST code is executed and the IPL can occur from a floppy diskette drive, a CD-ROM drive or the hard drive. In addition, if the computer is provided with a suitable adapter such as, for example, an IBM Auto Wake Token-Ring ISA Adapter and is connected to a computer network such as, for example, a local area network (LAN), there can be another potential source for the IPL operation. Namely, the IPL can occur from a remote storage location in a LAN server computer system (often called a remote IPL or RIPL).
Using the computer's ROM setup utility, a user can select which storage devices to IPL from and in what order to try each storage device when the system is powered on by the power switch. For example, the user can enter the configuration/setup utility by depressing the "F1"0 key during POST, select Start Options and then select Startup Sequence. From the Startup Sequence the user can choose the first, second, third, etc. startup devices. The user selections would be stored in a non-volatile memory of the computer system. If the user chose the following sequence 1-diskette drive, 2-hard drive and 3-network, then when the power switch is pressed, the POST code will first interrogate the floppy disk drive to test whether the drive contains a bootable diskette (i.e., whether a diskette is present and whether a valid boot record is held thereon). If it does, then the boot record on the diskette is used to control the initialization of the system. If there is not a bootable diskette in the floppy disk drive, then POST next interrogates the hard disk drive to test whether it has a valid boot record. If the hard drive does, then its boot record is used to control system initialization. If there is not a valid boot record stored on the hard drive, then POST next transfers control to RIPL ROM logic in the network adapter. The RIPL ROM logic will then attempt to establish a connection with a remote network server and enable the remote IPL of the operating system in a conventional manner. If after all these tests no valid boot record is found in any of the IPL devices an error message is displayed.
Current computer systems, however, have the ability to be powered on by several methods other than the power switch. For example, systems today can be powered on when a telephone ring is detected by a modem connected to the computer's serial port. In addition, the system can be programmed to turn on at a specific alarm time (wake on alarm). If the system is connected to a network, it can be remotely powered on across the LAN (wake on LAN). Current computer systems use the same ordered list of IPL storage devices regardless of whether the system is powered on by the power switch or by one of the other methods just mentioned. However, this is a disadvantage for users that want to use a different sequence when the system is powered on by other than the power switch.
For example, when powering on using the power switch a user may want to try the diskette drive first, and if there is no diskette inserted, IPL from the hard drive. However, when powering on because of being turned on by receipt of a "wake up" packet from the LAN, a user might want to RIPL from the LAN instead of booting from the diskette or hard drive. Currently, to do this, the user would need to invoke the ROM setup utility and change the boot sequence to have RIPL from the LAN as the first choice. However, once this is done, the system will attempt RIPL for all power on methods including if the system is powered on by the power switch.
It is therefore desirable to provide a computer system that allows a user to set the order of at least two different lists of IPL devices and select which list is to be used depending on the manner in which the computer system is powered on.